Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session B08: Animal Behavior |
Hide Abstracts |
Sponsoring Units: DBIO Chair: Prashali Chauhan, Syracuse University Room: Room 131 |
Monday, March 6, 2023 11:30AM - 11:42AM |
B08.00001: Fatal attraction: Electrostatic forces pull jumping nematodes directly to their charged prey Victor M Ortega-Jimenez, Sunny Kumar, Saad Bhamla Entomopathogenic nematodes are recognized as some of the smallest, most diverse, and highly specialized jumpers in the animal kingdom. It has been suggested that these microscopic parasites launch themselves violently into the air to reach their insect host. Most research on their locomotion abilities has been focused on their explosive jumping mechanism, which seems driven by elastic and capillary forces. However, how physical and environmental phenomena (such as electrical forces or the wind) impact their mid-air approach to prey is unknown. In particular, the influence of electrostatics is intriguing because it is well-known that flying insects can be easily charged during flapping or even when walking over plant litter. Here we present experimental results of how flow currents and exposure to electrically charged insects affect jumping Steinernema carpocapsae nematodes. Worms jumping against an airflow passively drifted downstream, significantly increasing their horizontal range. We discovered that electrically charged insects or even water droplets attract jumping nematodes. Thus, our results indicate that wind can be a fundamental driver for nematode dispersal and that electrostatic forces can significantly increase the likelihood of physical contact and attachment of a parasite to its prey. |
Monday, March 6, 2023 11:42AM - 11:54AM |
B08.00002: Water surface swimming dynamics via continuous contact in lightweight centipedes Baxi Chong, Kelimar Diaz, Steven Tarr, Eva Erickson, Daniel I Goldman Locomotion at the water surface is ubiquitous across scales (Bush and Hu, Annu. Rev. Fluid Mech., 2006). Previous studies on locomotors at the interface focused on propulsion emerging from limb-surface interactions. Less is known about how animals locomote via body-surface interactions, particularly with many limbs. Here, we discovered that a centipede, L. forficatus (N=8, L=2.3±0.3 cm, 14 leg-pairs), uses body-surface interactions to locomote at the water surface via direct waves of body curvature. Schlieren wave reconstruction of the water surface shows L. forficatus continuously emits water waves, relies on constant self-deformation for locomotion, and inertial forces are dominated by surface wave drag. Inspired by hispid flagella in microorganisms in viscous fluid, we posit forward motion using direct waves is achieved by modulation of the centipede’s ratio of local normal to tangential forces (drag anisotropy, less than one) due to its morphology. Thus, we modeled this centipede’s locomotion using surface wave RFT with experimentally resolved drag force relations of a centipede segment (slender body, extended limbs). Surface wave RFT predictions capture the animal’s swimming performance and shows the locomotor strategy facilitates high performance without introducing undesirable limb-body collisions, and potentially simplifying the animal’s neuromechanical control. |
Monday, March 6, 2023 11:54AM - 12:06PM |
B08.00003: Phase Transition in a Non-Markovian Animal Exploration Model with Preferential Returns ohad vilk, Michael Assaf, ran nathan, Daniel Campos, Vicenc Mendez We study a non-Markovian and nonstationary model of animal mobility incorporating both exploration and memory in the form of preferential returns. Exact results for the probability of visiting a given number of sites are derived and a practical WKB approximation to treat the nonstationary problem is developed. A mean-field version of this model, first suggested by Song et al., [Modelling the scaling properties of human mobility, Nat. Phys. 6, 818 (2010)] was shown to well describe human movement data. We show that our generalized model adequately describes empirical movement data of Egyptian fruit bats (Rousettus aegyptiacus) when accounting for interindividual variation in the population. We also study the probability of visiting any site a given number of times and derive a mean-field equation. Our analysis yields a remarkable phase transition occurring at preferential returns which scale linearly with past visits. Following empirical evidence, we suggest that this phase transition reflects a trade-off between extensive and intensive foraging modes. |
Monday, March 6, 2023 12:06PM - 12:18PM |
B08.00004: Thermodynamics of Animal Locomotion Éric Herbert, Christrophe Goupil Muscles are biological actuators extensively studied in the frame of Hill's classic empirical model as isolated biomechanical entities, which hardly applies to a living organism subjected to physiological and environmental constraints. We elucidate the overarching principle of a living muscle action for locomotion, considering it from the thermodynamic viewpoint as an assembly of actuators (muscle units) connected in parallel, operating via chemical-to-mechanical energy conversion under mixed (potential and flux) boundary conditions. Introducing the energy cost of effort as the generalization of the well-known oxygen cost of transport in the frame of our compact locally linear nonequilibrium thermodynamics model, we analyze oxygen consumption measurement data from a documented experiment on energy cost management and optimization by horses moving at three different gaits. Horses adapt to a particular gait by mobilizing a nearly constant number of muscle units minimizing waste production per unit distance covered; this number significantly changes during transition between gaits. The mechanical function of the animal is therefore determined both by its own thermodynamic characteristics and by the metabolic operating point of the locomotor system. |
Monday, March 6, 2023 12:18PM - 12:30PM |
B08.00005: 3-D pose estimation of larval zebrafish using an artificial neural network and a physical model Aniket Ravan, Martin Gruebele, Yann R Chemla Quantitative ethology requires an accurate estimation of an organism’s postural dynamics in three dimensions plus time. Technical advances over the last few decades have made animal posture estimation in challenging scenarios possible with unprecedented detail. Here, we present (i) a physical model-based method to generate realistic, annotated larval images in novel behavioral contexts, useful to train machine-learning algorithms, among other applications; (ii) an automated method to record and track the posture of individual larval zebrafish in a 3-D environment, applicable when accurate human labeling is too time-consuming; and (iii) a rich annotated dataset of 3-D larval poses for ethologists and the general zebrafish and machine learning community. Using three cameras calibrated with refraction correction, we record 3-D larval swims under free swimming conditions and in response to acoustic and optical stimuli. We then employ a convolutional neural network to estimate 3-D larval postures from these swims. The network was trained by a set of synthetic larval images rendered using a 3-D physical model of larvae. The physical model samples from a distribution of realistic larval postures estimated a priori by classical pattern recognition of larval swimming recordings, which, by itself would not be as accurate as the final neural network. Our final neural network model, trained without any human annotation, performs with a higher accuracy and speed than the classical approach, capturing detailed kinematics of 3-D larval swims. |
Monday, March 6, 2023 12:30PM - 12:42PM |
B08.00006: From 100k pigment cells to skillful camouflage: the role of skin color changes in sleeping octopuses Leenoy Meshulam, Aditi Pophale, Kazumichi Shimizu, Tomoyuki Mano, Sam Reiter Learning of a motor skill requires practice. Ample evidence suggests that ‘offline practice’ in the sleeping brains of animals, including humans, is crucial to any learning process. Offline practice allows for refining and consolidating neural activity pathways which are later executed during wake, which results in significant performance gains. However, in most animals, neural activity underlying offline practice is difficult to access and even more difficult to interpret. Therefore, the nature of neural activity underlying offline practice during sleep have remained elusive. Here, we study camouflage behavior in the octopus during wake and sleep. Octopuses possess the remarkable ability to rapidly modify pigment cells on their skin to match their highly visually complex environment. We combine high-resolution filming of their skin with electrophysiology recordings of their brain activity to capture the neural underpinnings of camouflage. Our theoretical framework captures the hierarchy of different spatial scales in the emergence of the octopus’ notable skin patterns and the dynamics of their transitions as they get reactivated on their skin during sleep. In addition, we bias the octopus experiences when awake to investigate the effect on the patterns’ reactivation during sleep. These findings elucidate how octopuses coordinate ~100k pigment cells to collectively give rise to highly intricate camouflage patterns, as well as the role of pattern reactivation during sleep. |
Monday, March 6, 2023 12:42PM - 12:54PM |
B08.00007: Sound of a handclap: An elastic Helmholtz resonator Yicong Fu, Akihito Kiyama, Sunghwan Jung Handclap is one of the most common human body languages for expressing approval and attracting attention. Despite the simple motion, numerous factors influence the acoustic output. Previous work on human subjects had suggested the relevance of hand configurations (Repp 1987). Nevertheless, the systematic study of the acoustic performance of a handclap has not been comprehensive. In preliminary studies, we observed an order of magnitude change in frequency with different cavity volumes and an amplitude change as a function of clapping speed. To further the understanding, we modified the traditional Helmholtz resonator model suggested by Fletcher (2013) to better capture the influence of cavity size, air outlet size, neck length, and clapping speed, experimentally. In addition, we considered the elastic modulus and deformation of the material for their effects on the frequency to discuss the validity and limitations of the proposed model. Reality-comparable reduced-order silicone hands for parametric studies were manufactured based on the dimensions from 3D scans of actual human hands. The frequency, amplitude, material dynamics, and fluid motion upon clapping were quantified from audio and high-speed images. Data from human subjects were also used to further verify the applicability of our experiment setup and validate our proposed theoretical model. |
Monday, March 6, 2023 12:54PM - 1:06PM |
B08.00008: A hinged jumping appendage helps terrestrial springtails direct their ultrafast jumps Jacob Harrison, Adrian Smith, Hungtang Ko, Saad Bhamla Many biological organisms (i.e., frogs, grasshoppers, and gall midges) use spring-latch mechanisms to generate ultrafast jumps and escape from potential predators. Directional control during escape jumps is important to effectively evade predators; however, in spring-latch systems, the ultrafast release of elastic energy can make energy flow difficult to control. Springtails (Collembola) are a group of non-insect hexapods that use a spring-latch jumping appendage called a furca to launch themselves off substrates at millisecond timescales. Here we look at whether terrestrial springtails have directional control over their spring-driven jumps. Using high speed video, we analyzed the takeoff kinematics of a terrestrial springtail ( Tomoceridae) leaping off of rigid substrates. Our experiments reveal a hinge in the springtail’s furca that help the springtail orient its ground reaction forces and gain forward momentum. Confocal microscopy of the furca shows that the hinge is a highly elastic structure that may passively absorb and release elastic energy at the millisecond time scale. Using mathematical modeling, we explore how the hinge affects the springtail’s jump and whether the hinge is necessary to orient ground reaction forces. Our findings offer novel insights into how ultrafast biological systems control their jumps and inform potential constraints on the flow of elastic energy through materials at millisecond timescales. |
Monday, March 6, 2023 1:06PM - 1:18PM |
B08.00009: Strong environmental forces induce a loss of wave coherence in C. elegans Christopher J Pierce, Lucinda Peng, Xuefei Lu, Daniel I Goldman, Hang Lu Undulation is a locomotor strategy employed by a large group of organisms that vary dramatically in scale and natural habitat. This form of locomotion generally involves the coherent propagation of waves of body curvature along the body of the organism, producing thrust. Coordination of undulatory waves is thought to be regulated by a quasi-redundant set of control mechanisms, 1) feedforward commands 2) sensory feedback and 3) passive mechanical processes that arise from physical body-environment interactions. The presence of strong environmental perturbations, such as obstacles or highly resistive media (e.g. packed soil), can disrupt wave coherence, producing more complex body kinematics (e.g. multi-frequency undulation, wave interference, quasi-periodicity, and aperiodic states). We describe the origin of these behaviors in the mm-scale nematode C. elegans moving in viscoelastic gels (bulk modulus ~1-50nN/ μm2) by isolating environmental effects on the various control systems. Exploiting its suite of available genetic tools, we performed functional imaging of muscle activity and also compared the loss of wave coherence in mutants with defective mechanosensory feedback mechanisms (local proprioception and global touch sensation) to wild-type animals. Our results suggest that environmental perturbations affect multiple control systems to induce incoherent undulatory dynamics under increasing environmental forces, producing the observed behavioral complexity. |
Monday, March 6, 2023 1:18PM - 1:30PM |
B08.00010: Turning behavior of freely-walking Drosophila in response to the timing of odor encounters Viraaj R Jayaram, Aarti Sehdev, Nirag Kadakia, Ethan A Brown, Thierry Emonet To survive, insects must use information from complex odor plumes to navigate to their source. In natural plumes, turbulence breaks up smooth odor regions into discrete packets, so navigators encounter brief bursts of odor interrupted by bouts of clean air. The timing of these encounters plays a critical role in navigation, modulating decisions to change orientation and walking speed. However, disambiguating the role of odor timing from other cues, such as spatial structure, is challenging due to natural correlations between plumes’ temporal and spatial features. Using optogenetics, we isolated the temporal features of odor signals, examining how signal frequency and duration shape the navigational decisions of freely-walking Drosophila. Analyzing the effect of these stimuli on flies’ turning behavior revealed a type of novelty detection: response to new (virtual) odor packets was larger when the most recent packet was sufficiently far in the past. Analysis also revealed behavioral changes over fast and slow timescales, allowing for responses to signal offset and sustained upwind bias across environments. These features are captured by a single mathematical model that predicts Drosophila orientation dynamics in the 45 temporally diverse environments tested. I will conclude by explaining how this combination of fast and slow timescales might emerge from known dynamical properties of neurons in the olfactory circuit, and how this enhances navigation towards odor sources in diverse environments. |
Monday, March 6, 2023 1:30PM - 1:42PM |
B08.00011: Long term recordings of Drosophila melanogaster behavior at high temporal resolution Grace C McKenzie-Smith, Scott W Wolf, Julien F Ayroles, Joshua W Shaevitz Behaviors evolve over many different timescales, from the short, seconds-long individual articulations required for vocalizations to the sometimes decades-long process of aging. Initial forays into uncovering the long timescale structure of behavior have shown that behavior evolves in a non-Markovian fashion, and is hierarchically organized in some systems1. However, these studies have been limited to the approximately hour-long timescales of the previously available behavioral datasets. We have developed a method to take continuous, high-dimensional, high-resolution behavioral data of the freely moving fruit fly Drosophila melanogaster spanning days and weeks. We apply modern techniques of pose-estimation (SLEAP)2 and computational ethology (MotionMapper)3 to quantify the behavior of recorded flies, and use these data to study circadian features of behavior, and to characterize how D. melanogaster's habituation to novelty varies in different behavioral modes across days. We are also studying how behavior changes with age, and how early life behaviors may predict later activity. |
Monday, March 6, 2023 1:42PM - 1:54PM |
B08.00012: Integrating pose estimation with tag-based tracking to capture dense social networks Scott W Wolf, Dee M Ruttenberg, Daniel Y Knapp, Andrew E Webb, Ian M Traniello, Grace C McKenzie-Smith, Sophie Leheny, Joshua W Shaevitz, Sarah D Kocher The drive to study the behavior of animals living in groups has motivated a vast expansion of behavioral tracking technology. Much of this technology relies on pose estimation tools, such as SLEAP [1], which accurately track the location of individual body parts of the animal. Moreover, they enable the analysis of complex behaviors which cannot be studied by looking at centroids alone, such as communication via specialized sensory systems or aggressive behaviors like mounting, biting, or stinging. While SLEAP and similar frameworks are able to track and maintain the identity of small numbers of animals, they perform poorly when the number of animals becomes very large, animals are allowed to exit and enter the frame, or when the identity of each animal must be maintained across experiments. Past solutions for monitoring many animals use externally applied tags, such as bar codes or paint dots, to uniquely identify individuals but these techniques do not record pose. We present NAPS (NAPS is ArUco Plus SLEAP), a hybrid behavioral tracking framework that combines state-of-the-art, deep learning-based methods for pose tracking (SLEAP) with unique markers for identity persistence (ArUco) and show that we are able to capture pose and identity within dense social networks in complex environments. We analyze the dynamics of colonies of approximately 50 bumblebees and show that NAPS outperforms SLEAP or ArUco alone. |
Monday, March 6, 2023 1:54PM - 2:06PM |
B08.00013: Emergence of long time scales in a fluctuating landscape picture of animal behavior Antonio Carlos Costa, Massimo Vergassola Animal movement exhibits multiple time scales: from the fine-scale movements of the limbs, to the behavioral sequences that result in different search strategies, all the way up to aging. Here, we hypothesize that the multiplicity of scales inherent to behavior effectively breaks ergodicity, preventing the system from reaching a steady state within experimental time scales. This motivates a phenomenological picture in which the behavioral dynamics evolve in a fluctuating potential landscape: the different wells correspond to stereotyped movements while the potential itself fluctuates reflecting slow changes in strategies or internal states. Under general assumptions for the underlying dynamics, we show that driving the potential landscape slowly and strongly enough results in the emergence of heavy-tailed first passage times, which asymptote to a power law with an exponent of -2. In addition, we find that nontrivial long-range correlations emerge when the system evolves on time scales comparable to the measurement time. Finally, we illustrate these results in the behavior of the nematode C. elegans, in which a slowly varying potential landscape accurately predicts the nontrivial statistical properties of the dynamics. Such inferred slow dynamics reflect underlying neuro-physiological patterns, opening up new paths for the understanding of how such internal states are generated and controlled by the organism. |
Monday, March 6, 2023 2:06PM - 2:18PM |
B08.00014: Data-driven discovery of long timescale behavioral strategies during sensory evoked locomotion Gautam Sridhar, Antonio Carlos Costa, Massimo Vergassola, Claire Wyart Survival requires the animal brain to generate flexible and adaptive behavioral mechanisms on multiple timescales. To identify the internal states that modulate behavior across scales, we require an understanding of how short timescale behaviors are chained to generate long sequences. We leverage the larval zebrafish to characterize such sequences because of the availability of high-resolution, high throughput recordings in various sensory conditions. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700